Have you tried "doping" your speaker cones?


I recently "doped" my cones. I had read several discussions on it, on the Single Driver Website. It seems Damar varnish is the "dope" of choice. I couldn't find that brand so I used another. I thought it made a fantastic difference. The cones are much stiffer and there is better definition and smoother high end. Bass tightened up too. Had to make a slight adjustment in the "stuffing" in my transmission line tube to cut the bass back a little. They recommend two coats, so that's what I did. Anyone else tried it?
twl
Everbody talks about light moving mass but many speaker manufaturers modify the drivers they use by adding damping material. An older Dalquast(sp) Moniter had some sort of putty on the front of the woofer. someone was marketing a doping mod for Mission 707s. One of the most highly rated speakers today use a "damping ring"(my term) applied to the back of magnesium mid-woofers.
Twl, how could you do that ? What you did is both illegal and immoral. This is not to mention that you might have even gotten your drivers "hooked". For shame, for shame...

Actually, i've heard many positives about doing something like that. I can see how it could help in reducing cone break-up, flexing and distortion. As you mentioned, i think that it is most beneficial in the upper mids and treble.

Out of curiosity, does the driver that you are using have a whizzer cone and if you've done anything to work with that ? Sean
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Sean, I've not only got my drivers "hooked" on doping, but I've got myself hooked at the same time. It really worked exactly as I thought. Great fine-tuning tweek. Only adds a few grains of weight, but alot of stiffening. About the whizzer cone mods, mine don't have any, but I've heard of 2 mods for them. They both are aimed at reducing the whizzer cone's propensity to vibrate out-of-control at the unsupported outer edge. This is the cause of the upper mid anomaly commonly known as "Lowther Shout", and some "tizzly" high end effects. One mod uses fiber glass insulation material, the other uses lamb's wool. In either case, a small amount of material is gently tucked in and lightly glued between the back of the whizzer cone and the main cone. All the way around. The idea being to support and damp the whizzer cone without adding any more mass than absolutely necessary. I have not tried this myself, and the Lowther people don't recommend it, but I have read many posts and articles that said it helped. This idea could be tried on any whizzer cone driver that is exhibiting peaky and irritating upper mids and highs. And if you don't like it you can take it out. That "glue stick" like kids use in school is good for temporary testing purposes. Albert - I guess this mod is how to get the "whiz" out of the whizzer!
The big problem I see with this is that it is not reversible. What do you do if it sounds worse? If the drivers are cheap it might be worth a try.

You can get dope at your local hobby shop. Model airplane builders put it on the paper wings to make them stronger.

Twl, what kind of drivers are you doping?